Created attachment 8963[details]
Patch to fix broken x32 overflow checks
Fix incorrect x32 overflow checking for refs to weak undef symbols.
On x32, a pc-relative reference to an undef weak symbol (value 0)
with a negative addend (typically -4) generates a spurious overflow
error because Symbol_value::value() returns a 32-bit negative number
as an unsigned number, which gets zero-extended before subtracting
the PC value. This patch fixes the problem by special-casing the
negative addend, and adding it to the value after widening it to
64 bits. Symbol_value::value() does not need the addend if it's
negative, since it is only important when processing section
symbols for merge sections, where a positive addend provides the
input section offset of the merged constant.
With this patch, I can build basic_static_pic_test in x32 mode.
HJ, I'd appreciate it if you could give it more testing before I
commit it.
2016-02-06 Cary Coutant <ccoutant@gmail.com>
gold/
* x86_64.cc (X86_64_relocate_functions::pcrela32_check): Fix x32
overflow checking when symbol value + addend < 0.